See 10 Best Hearing Aids of 2018

A Glossary of Hearing Aid Terms

Jim TrummFeb 28, 2018

Hearing aids are complex devices designed to compensate for many different kinds of hearing loss. Here's a guide to technical and medical terms you may come across as you determine device is right for you. We believe this document to be the most complete glossary of consumer-oriented hearing aid terms on the net, but if you see something we've missed, please email


Auditory Brain Stem Response. See BERA test.

Age-related hearing loss

As people get older, their ability to hear higher frequencies often degrades. This sensorineural condition, technically known as presbycusis, is the most common type of hearing loss and generally afflicts people in both ears.


The electronic components in a hearing aid that make the sound louder. In essence, hearing aids consist of a microphone which receives the sound, an amplifier which boosts the sound, and a speaker.


An older amplification technology that boosts the volume of a given input but does not filter out background noise or other non-speech sounds.

Attack and release times

The time that elapses between the moment a hearing aid "hears" a volume increase or decrease and the moment it adjusts its amplification accordingly. The shorter these times are, the less likely that a user will be jolted by a sudden increase in volume level or has to strain to catch what was said when there is a sudden decrease in volume level.

Audio shoe

A device that feeds a sound signal directly into a behind-the-ear (BTE) hearing aid. The signal can come from a microphone or from a cable connected to a radio, music player, or TV. The device is also known as an Audio boot.


A curve on a graph based on a hearing test that visually documents your how well you hear different sounds in each ear.


A device used to test people's hearing. The equipment produces sounds of various frequencies and volume levels, which enables a technician to determine how well you hear different sounds.

Automatic gain control

A part of a hearing aid that automatically limits or adjusts a hearing aid's volume (gain) so that it will be neither too loud nor too soft.


Bone Anchored Hearing Aid. This is a two-part hearing aid that consists of a titanium implant that is fastened into the patient's skull behind the ear. A tiny jack protrudes through the skull. A small sound processor can be plugged into the jack on the outside of the skull. This device receives sound waves and transmits them directly through the bone of the skull to the ear, bypassing the middle ear entirely and resonating in the cochlea in the inner ear.

BERA test

Brainstem Evoked Response Audiometry determines how well sounds are communicated from the inner ear to your brain. Also known as an Auditory Brainstem Response (ABR) test.


Bilateral Microphones with Contralateral Routing of Signal. This refers to the amplification technology that is employed when a patient experiences hearing loss in both ears, with one side hearing significantly better than the other. See CROS.

Binaural synchronization

Binaural synchronization (also known as binaural coordination) is a technology that mutually shares and processes the inputs from both a left and a right hearing aid. This permits the signals to be more effectively and accurately processed. It's particularly effective at zeroing in on speech in a noisy environment. It also allows the user to adjust both hearing aids simultaneously by changing a single setting.

Bluetooth connectivity

Bluetooth is a radio technology that permits devices to share information over short distances. The technology enables hearing aids to connect wirelessly to telephones, televisions, home entertainment systems, and the like.


Behind the Ear. In this type of hearing aid, the microphone, processor, and amplifier are enclosed in a "case" that rests behind the ear. Sound travels through a tiny tube into an ear mold that fits snugly into the ear canal.


Most hearing aids can be set to amplify and clarify different channels, which are simply frequency ranges. One channel might amplify high tones, while another might amplify midrange tones, and another low tones. Generally speaking, the more channels a hearing aid has, the more accurately it can accommodate to a particular person's hearing loss.


Completely-in-the-canal. A hearing aid that is inserted in the ear canal and cannot be seen from the outside. It can be removed by pulling on the small transparent stick that protrudes from it.


A part of the inner ear that's shaped like a spiral and is full of fluid. Vibrations from the hearing bones in the middle ear are transmitted to the fluid. Hair cells in the Cochlea translate those vibrations into electric signals that are transmitted to the hearing nerve. Sensorineural hearing loss may result if those hair cells are damaged or do not work properly.

Combined hearing loss

A description of someone who has both conductive and sensorineural hearing losses.


The process by which some hearing aids lower the frequency of higher-pitched sounds to make them more audible for patients who have lost part of their upper hearing range. As people age, it often becomes more difficult for them to hear higher-pitched sounds. Merely amplifying higher-pitched speech is not an optimal solution, because at louder volume levels speech can become less intelligible. So some newer hearing aids "compress" high-pitched speech into lower tones, making it easier to hear and understand.

Conductive hearing loss

Hearing loss caused by the failure of the middle or outer ear to conduct sounds into the inner ear where the hearing nerves are. This may be caused by a blockage in the hearing canal—usually ear wax. It may also be the result of damage to or malformation of the hearing canal or the ear drum, or a build-up of fluid behind the ear drum. The condition is usually reversible.


The hair cells in this organ convert the vibrations in the middle ear into electrical signals, which feed in to the hearing nerve and enable the brain to experience and identify sounds.


Collateral Routing of Signals. This technology is used to help people who suffer hearing loss in one ear. It collects sound from the ear with poorer hearing and transmits it wirelessly to the ear with better hearing.

DAI port

A direct audio input port is a three pin port (or jack) that's found on many BTE hearing aids. The port enables hearing aid wearers to receive audio directly from computers, phones, music players, or televisions. DAI ports also connect audio shoes.

Decibel (dB)

A unit of sound, with 0 dB being the quietest sound a person with normal intact hearing is capable of perceiving. Patients who can only hear sounds on a given frequency that are 20 dB and louder are deemed to have hearing loss.

Digital hearing aid

In contrast with older, analog hearing aids, digital hearing aids don't just amplify sounds, they process and manipulate them. Sounds received by these devices are converted to bits, which can be manipulated in almost infinite ways. They do a much better job than older designs at filtering noise and improving the signal-to-noise ratio.

Directional mechanism

A technology that enables hearing aids to emphasize some sounds and de-emphasize others, depending on the type and location of the sound. Usually these mechanisms are set so that speech coming from in front of the patient are given priorities while sounds coming from behind or beside the patient are muted.

Ear mold

The part of a BTE hearing aid that conducts sounds from the external amplifier into the hearing canal. The mold is usually made of silicon and is fit to the unique contours of a patient's ear.

Extended wear

An extended wear hearing aid is inserted deep inside the ear canal and is worn for several months at a time without removal. It is generally prescribed for people with mild to moderately severe hearing loss. They generally have to be removed by a hearing practitioner when the battery needs to be replaced.


A sound produced when a microphone picks up some of the sound coming from an amplifier. It usually sounds like a high-pitched squeal, whistle, or squawk. It can occur in hearing aids when a sound that's already been amplified leaks from inside the ear to a hearing aid microphone located outside the ear.


A filter lets a hearing aid user amplify some frequencies and de-emphasize other frequencies so they won't be amplified. People with high frequency hearing loss may want to filter lower-frequency sounds so they won't be amplified.

Hearing loss

A decrease in the ear's sensitivity to sounds. It is categorized by severity (how much one has to amplify a sound for it to be heard) and type (the cause of the hearing loss).

Hertz (Hz)

Formerly known as cycles per second, this is a measure of frequency, that is, how high or low a tone is. Human beings can generally hear sounds that range from 20Hz to 20,000Hz.


Invisible in-canal hearing aids. These custom-made devices fit completely inside the ear canal and are inserted and removed by a tiny clear plastic "cord" that protrudes from them.


Implants are surgically-attached devices that consist of an electrode that is inserted into the cochlea, where it can stimulate and hearing nerve directly. They work with an external microphone and processor which collects sound and transmits it to the electrode. These devices are used only in patients with very significant hearing loss.


In-the-canal hearing aids. These are very small hearing aids that sit in the ear canal, but whose outer parts can be seen at the mouth of the ear canal.


In-the-ear hearing aids. These devices are placed in the outer ear and tend to be larger and more visible than other styles.


Localization is the process by which our two ears, working together and sending signals to the brain, can help a person understand where sound is coming from.


A situation where louder sounds interfere with people's ability to hear or understand softer sounds.

Middle ear

The area between the ear drum and the inner ear. Three small hearing bones (ossicles) there conduct sound from the ear drum to the fluids in the inner ear.

MCL (Most Comfortable Level)

The level of volume that feels the best for a particular person. This is a subjective assessment that varies with the person. People with good hearing will likely experience the volume of normal conversation as the MCL for him or her.

Mini BTE

A newer, smaller, sleeker version of behind-the-ear hearing aids that are less visible than older models.

Noise canceling mechanism

Any technology that attempts to avoid the amplification of background noises by "cancelling" them before they reach the output stage of a hearing aid.

Open fit

An open fit hearing aid allows low tones to pass through a ventilation tunnel and to be heard naturally, while at the same time amplifying higher-pitched tones.


See age-related hearing loss.


Some hearing aids allow their users to select (or even design) an array of settings-i.e., programs-that are designed to work optimally in a specific environment. For example, one program might be optimized for a hearing what's said onstage during a play. Another might be optimized for driving. Another might be optimized for noisy work environments. Some hearing aids now come with adaptive programs that "learn" the user's preferences and switch from program to program automatically.


A phenomenon where a person with hearing loss feels that voices and other sounds are louder than how they are perceived by a normal hearing person. People who experience this may experience discomfort when listening to speech that a normal hearing person would characterize as loud, but not uncomfortable. The phenomenon is due to the fact that hearing loss usually entails a contraction of the hearing range at both the loud and soft ends. This puts people with hearing loss in the paradoxical position of not being able to hear soft sounds and not being able to tolerate loud ones.

REM (Real Ear Measurement)

The analysis of how sounds produced by a hearing aid are received inside the ear. REM determines whether a hearing aid produces optimal sound improvement once it is in a specific person's ear.


Receiver-in-canal designs are a type of behind-the-ear hearing aids. Sound is collected by a behind-the-ear unit and fed by a tube into a receiver, which is located inside the ear hearing canal. Their close proximity to the ear drum allows these units to consume less power and produce less sound than other designs.


Receiver-in-the-ear designs are a type of behind-the-ear hearing aids. They transmit sound to a receiver that is placed outside in the hollow by the entrance to the ear canal

Sensorineural hearing loss

Hearing loss caused by damage to the inner ear or the hearing nerve. Sensorineural hearing loss typically causes a higher hearing threshold and impairs people's understanding of human speech. It can be the result of congenital conditions, aging, exposure to loud noise, hearing nerve tumors, and various diseases and toxins. In contrast to conductive hearing loss, this condition is usually not fixable.

Shape (of hearing loss)

The shape of the graph that appears on an audiogram (see above). Different shapes are described in various ways, including "flat" (the same hearing threshold on all hearing frequencies), "HTL" (high tone loss), "LTL" (low tone loss), "U shape" (hearing that is better at the high and low tones and worse at the middle tones), "corner" (patient can hear low tones but not middle or high ones), and "dead ear" (deaf to all frequencies).

Signal to Noise Ratio (SNR)

Signals refer to sounds people want to hear, such as human speech. Noise refers to background and unwanted sounds. The signal to noise ratio is an expression of the relative strength of these two types of sounds. In most cases, the better the SNR, the easier it is for hearing aid wearers to understand speech.

Sound impulse management

A technology that identifies, isolates, and softens sudden distracting noises so that the wearer of a hearing aid can focus on desired sounds (e.g., speech) and not be made uncomfortable by the amplification of crashes, clatters, bangs, and other disruptive sounds.


A small coil inside a hearing aid that picks up electromagnetic signals, such as those coming from telephone receivers and headphones and converts them directly into sound. This is often an effective method for people with hearing loss to use sound-producing electronic devices.


A person's hearing threshold is the quietest sound he or she can detect. Hearing threshold is usually tested on several frequencies that are produced in typical human speech.


A sensation of noise is not caused by an external source, frequently described as a ringing, hissing, roaring, booming, or whistling in the ears. It's frequently a symptom of hearing loss. Some hearing aids can compensate for tinnitus by producing a screening sound that masks the condition.


A tiny, flexible, transparent channel connecting a BTE hearing aid to its ear mold. Sound enters the microphone in the BTE, is amplified, and is sent through the tube into the ear.


A test designed to reveal problems in the middle ear. A clinician uses an instrument that blows puffs of air into the ear at different pressures. The way the ear drum responds shows the condition of the middle ear.


Uncomfortable level of sound, i.e., the loudest sound level someone can experience without being made uncomfortable. 

Now that you know the lingo, head over to our list of the Top Ten Hearing Aids and check them out for yourself.